Boot hang on BETA2

[Patrick Collison]

I'm fairly new to FreeBSD, but I've been using 5.2.1 for a while 
without any major problems. When I tried 5.3-BETA2 today, the boot hung 
repeatedly after `acd0: DVDROM <_NEC DV-5700A/3.97> at ata1-master'. 
Safe mode, disabled ACPI, etc, all make no difference.

 From a quick browse of the archives, it seems that a few others have 
shared the same or similar problem. Any sign of a fix?